Jaycie Howard, 5, comes to the realization her dad, Ryan Howard, is on the Allegiant Air flight from Orlando, Fla., as he disembarks at the Owensboro-Daviess County Regional Airport Friday afternoon. Her dad had been working construction in Florida and mom, Crystal Howard, right, and uncle and aunt, Alan and Sandy Ebelhar, had kept it a secret up until the moment she spotted him. DENNY SIMMONS / COURIER & PRESS

As Evansville celebrates the arrival — and rapid expansion — of Allegiant service, words of caution abound that the routes may be short-lived. Perhaps no entity is more honest about that than Allegiant itself. The airline’s rallying cry to the communities it serves: Use it or lose it.

“Allegiant’s pretty agile,” said Kristen Schilling-Gonzales, the airline’s director of planning. “We’re monitoring every flight. We’re looking at every route we operate on a monthly basis, quarterly basis, even more than that.”

Allegiant is unique in that even seemingly successful service sometimes finds itself on the chopping block.

An Alaska/Horizon Bombardier Q400 painted in an Oregon Ducks livery taxis for departure as a Virgin America Airbus A319 takes off from Seattle-Tacoma International Airport on Dec. 24, 2016. Jeremy Dwyer-Lindgren, special for USA TODAY

That's because Allegiant's low-cost fares are dependent upon its ability to up-sell customers on everything from seat selection to hotel rooms. Jets full of frugal passengers who paid for their flights, but nothing else, end up costing the airline money.

In regulatory filings, the company said it averages expenses of about $100 per passenger per flight, or $200 round trip. As an airline that routinely offers round trip fares as low as $100 on flights, Allegiant needs to sell customers rental cars and tickets to events to make those routes profitable.

“If you took just our airfares alone, that doesn’t cover our costs. That’s honest,” Schilling-Gonzales said. “So we do offer ancillary products as a way to let customers customize their vacations.”

Et tu, Allegiant?

Few airlines tweak their route maps as frequently as Allegiant. While legacy carriers, such as American, Delta and United, are more apt to play the long game when it comes to allowing new routes to perform, Allegiant opts for a different approach.

Take Owensboro. At one point, Allegiant flew four round-trip flights per week between Orlando and Owensboro, as well as the twice-weekly Las Vegas flight.

"We were very elated that we had non-stop flights to two of the most popular vacation destinations in the United States," Whitmer said. "It was a very attractive offering we had at our airport. We were extremely pleased."

Today, Allegiant only flies twice-weekly Orlando flights.

While Allegiant still serves Owensboro, there are plenty of other airports — including Casper, Wyo.; Akron-Canton, Ohio; and Youngstown-Warren, Ohio, — where Allegiant has departed completely.

When Allegiant left Casper, "they never issued a news release," Airport Director Glenn Januska said. "They took the service out of the schedule, and I think the only way people would have known that the service was going to be discontinued was they went to book a flight and noticed, 'Hey, wait a minute. Casper isn't there anymore.'"

At Youngstown-Warren, which lies between Cleveland and Pittsburgh, Allegiant — in its trademark honesty — "told us, straight up, we can make more money at the larger airports," Aviation Director Dan Dickten said.

Now you see it ...

While some airports grapple with the loss of Allegiant service, the opposite is true in Evansville.

Two years ago, Allegiant didn’t even have Evansville on its route map. Then it added twice-weekly Orlando flights, followed by a third weekly Orlando flight, and then a second destination: Destin, Fla.

How long the good times will roll remains up in the air. For every Casper, Akron or Youngstown there are dozens of airports that 21-year-old Allegiant has served uninterruptedly for a decade or longer.

Allegiant says it's committed to serving both Evansville and Owensboro, even though they're only about 40 miles apart by car.

"There are increased costs by operating both airports, but we think it’s a bigger, larger revenue benefit by serving both airports and passengers in both cities," Schilling-Gonzales said.

Flights to Orlando from Evansville operate on Tuesdays, Thursdays and Sundays, while flights from Owensboro operate on Mondays and Fridays. Some passengers fly from one airport and back to another depending on what best meets their schedule, Schilling-Gonzales said.

But if Youngstown-Warren is any indication of Allegiant's business model, service to Owensboro may not be long for this world.

"We could kind of see the handwriting on the wall," Dickten said. "Our schedule started to change. We lost Punta Gorda (in southwest Florida) back in 2015-2016. Then we started getting some of the schedules that weren't during the prime time — more late in the evening, and this and that."

That's exactly what's happening in Owensboro, which lost its Las Vegas flight, then some of its Orlando flights and then more optimal schedules.

Allegiant's flights from Owensboro often are the last to land at Orlando. Delays regularly push arrival times past midnight.

Allegiant spokeswoman Courtney Goff said the airline is committed to serving both Evansville and Owensboro and splitting airport fees between the two cities.

"In the instance of right now, where we have these two separate airports, we're able to keep the costs as low as we can to passengers," she said. "We could decide something different tomorrow."

The next five years

Allegiant has suffered its fair share of bad publicity for wounds both superficial and self-inflicted.

The airline gained some notoriety when it announced new routes only to pull the service before a single jet took off. That's a practice the airline has stopped.

"We usually extend our schedule four times a year rather than having an ongoing schedule," Schilling-Gonzales said. "When we release that schedule, that's pretty well what we intend to operate at those times. We've been conscientious about putting routes on sales that we were operating at the times, at the days, we said we would. We've gotten a lot better at it over the past couple of years."

With its fleet of about 100 jets — many of them only a few years old — Allegiant constantly surveys markets to see if moving a jet from, say, Owensboro to Evansville will make the company more money.

"We've always known if the market was not doing what they needed from a revenue standpoint that they could take that airplane and put it someplace else where they think they can generate more money," Januska, the Casper airport director, said of that market. "That's a business decision."

Former and current United Airlines employees who had served on the Boeing 727 pose in front of the first of the type after its final flight at the Museum of Flight in Seattle on March 2, 2016. Jeremy Dwyer-Lindgren for USA TODAY

A delightfully dated interior graces the cabin of the first Boeing 727, which completed its last flight on March 2, 2016, in Seattle. It is now on permanent display at the Museum of Flight. Jeremy Dwyer-Lindgren for USA TODAY

A heavy-duty .50-calibur machine gun, no longer active, keeps watch over North Seattle during a flight aboard a 71-year-old restored B-24 World War II-era bomber on June 26, 2015. Jeremy Dwyer-Lindgren for USA TODAY

Col. Ken Wheeler, a 92-year-old World War II veteran and B-17 bomber navigator, pauses to study a .50-calibur heavy machine gun while on a World War II-era B-24 bomber flight over Seattle on June 26, 2015. Jeremy Dwyer-Lindgren for USA TODAY

The soon-to-be home of Southwest Airlines in Houston Hobby is seen under construction on June 19, 2015. The ticketing concourse is part of the new international terminal, set to open later this year. Jeremy Dwyer-Lindgren for USA TODAY

An escalator stands ready to shuttle Houston Hobby's soon-to-come international passengers to customs inside the airport's international terminal, still under construction, on June 19, 2015. Jeremy Dwyer-Lindgren for USA TODAY

The new home of Southwest Airlines in Houston Hobby is seen under construction on June 19, 2015. The ticketing concourse is part of the new international terminal, set to open later this year. Jeremy Dwyer-Lindgren for USA TODAY

The soon-to-be home of Southwest Airlines in Houston Hobby is seen under construction on June 19, 2015. The ticketing concourse is part of the new international terminal, set to open later this year. Jeremy Dwyer-Lindgren for USA TODAY

About to end a 16+ hour journey, an Emirates Airbus A380 superjumbo sails over a Boeing 747-8 as it lands at Houston's George Bush Intercontinental Airport on June 19, 2015. Jeremy Dwyer-Lindgren for USA TODAY

The distinct blue, white and gold globe of United Airlines repeats itself on a series of Boeing 737s at Houston's George Bush Intercontinental Airport on June 19, 2015. Jeremy Dwyer-Lindgren for USA TODAY

Banks of computers and test equipment line the interior of Boeing's ecoDemonstrator 757, seen during a media tour in early June 2015. The airplane tests a variety of new technologies on board, including non-stick wing surfaces to reduce bug residue. Jeremy Dwyer-Lindgren for USATod